r5.metal and r5d.metal instances provide your applications
with direct access to physical resources of the host server, such as processors and
memory. These instances are well suited for the following:

Workloads that require access to low-level hardware features (for example, Intel VT)
that are not available or fully supported in virtualized environments

Applications that require a non-virtualized environment for licensing or support

High memory instances (u-6tb1.metal, u-9tb1.metal, and u-12tb1.metal) offer 6 TiB, 9 TiB, and 12 TiB of
memory per instance. These instances are designed to run large in-memory databases,
including production installations of SAP HANA. They offer bare metal performance
with direct access to host hardware.

X1 Instances

These instances are well suited for the following applications:

In-memory databases such as SAP HANA, including SAP-certified support for Business
Suite S/4HANA, Business Suite on HANA (SoH), Business Warehouse on HANA (BW), and
Data Mart Solutions on HANA. For more information, see SAP HANA on the AWS
Cloud.

Memory Performance

For more information about how much RAM can be enabled for memory optimized instances,
see Hardware Specifications.

Memory optimized instances have high memory and require 64-bit HVM AMIs
to take advantage of that capacity. HVM AMIs provide superior performance in
comparison to paravirtual (PV) AMIs on memory optimized instances. .

Instance Performance

R4 instances feature up to 64 vCPUs and are powered by two AWS-customized Intel XEON
processors based on E5-2686v4 that feature high-memory bandwidth and larger L3 caches
to boost the performance of in-memory applications.

X1e and X1 instances feature up to 128 vCPUs and are powered by four Intel Xeon E7-8880
v3
processors that feature high-memory bandwidth and larger L3 caches to boost the performance
of in-memory applications.

High memory instances (u-6tb1.metal, u-9tb1.metal, and u-12tb1.metal) are the first instances to be
powered by an eight-socket platform with the latest generation Intel Xeon Platinum
8176M
(Skylake) processors that are optimized for mission-critical enterprise workloads.

Instance types that use the Elastic Network Adapter (ENA) for enhanced networking
deliver high
packet per second performance with consistently low latencies. Most applications do
not consistently need a high level of
network performance, but can benefit from having access to increased bandwidth when
they send or receive data. Instance sizes
that use the ENA and are documented with network performance of "Up to 10 Gbps" or
"Up to 25 Gbps" use a network I/O credit
mechanism to allocate network bandwidth to instances based on average bandwidth utilization.
These instances accrue credits
when their network bandwidth is below their baseline limits, and can use these credits
when they perform network data transfers.

The following is a summary of network performance for memory optimized instances that
support enhanced networking.

SSD I/O Performance

If you use all the SSD-based
instance store volumes available to your instance, you get the IOPS (4,096 byte
block
size) performance listed in the following table (at queue depth saturation). Otherwise,
you get lower IOPS performance.

Instance Size

100% Random Read IOPS

Write IOPS

r5ad.large *

30,000

15,000

r5ad.xlarge *

59,000

29,000

r5ad.2xlarge *

117,000

57,000

r5ad.4xlarge *

234,000

114,000

r5ad.12xlarge

700,000

340,000

r5ad.24xlarge

1,400,000

680,000

r5d.large *

30,000

15,000

r5d.xlarge *

59,000

29,000

r5d.2xlarge *

117,000

57,000

r5d.4xlarge *

234,000

114,000

r5d.8xlarge

466,666

233,333

r5d.12xlarge

700,000

340,000

r5d.16xlarge

933,333

466,666

r5d.24xlarge

1,400,000

680,000

r5d.metal

1,400,000

680,000

z1d.large *

30,000

15,000

z1d.xlarge *

59,000

29,000

z1d.2xlarge *

117,000

57,000

z1d.3xlarge *

175,000

75,000

z1d.6xlarge

350,000

170,000

z1d.12xlarge

700,000

340,000

z1d.metal

700,000

340,000

* For these instances, you can get up to the specified performance.

As you fill the SSD-based instance store volumes for your instance, the number of
write IOPS
that you can achieve decreases. This is due to the extra work the SSD controller
must do to
find available space, rewrite existing data, and erase unused space so that it
can be
rewritten. This process of garbage collection results in internal write amplification
to
the SSD, expressed as the ratio of SSD write operations to user write operations.
This
decrease in performance is even larger if the write operations are not in multiples
of
4,096 bytes or not aligned to a 4,096-byte boundary. If you write a smaller amount
of bytes
or bytes that are not aligned, the SSD controller must read the surrounding data
and store
the result in a new location. This pattern results in significantly increased write
amplification, increased latency, and dramatically reduced I/O performance.

SSD controllers can use several strategies to reduce the impact of write amplification.
One such strategy is to reserve space in the SSD instance storage so that the controller
can more efficiently manage the space available for write operations. This is called
over-provisioning. The SSD-based instance store volumes provided to
an instance don't have any space reserved for over-provisioning. To reduce write
amplification, we recommend that you leave 10% of the volume unpartitioned so that
the SSD
controller can use it for over-provisioning. This decreases the storage that you
can use,
but increases performance even if the disk is close to full capacity.

For instance store volumes that support TRIM, you can use the TRIM command to notify
the SSD controller whenever you no longer need data that you've written. This provides
the
controller with more free space, which can reduce write amplification and increase
performance.
For more information, see Instance Store Volume TRIM Support.

Instance Features

The following is a summary of features for memory optimized instances.

In addition, you can implement high availability (HA) and disaster recovery (DR)
solutions to meet recovery point objective (RPO), recovery time objective (RTO), and
cost requirements by leveraging Amazon
CloudFormation and Recover Your Instance.

Support for vCPUs

Memory optimized instances provide a high number of vCPUs, which can cause launch
issues
with operating systems that have a lower vCPU limit. We strongly recommend that you
use
the latest AMIs when you launch memory optimized instances.

R5, R5a, R5ad, and R5d instances support
a maximum of 28 attachments, including network interfaces, EBS volumes, and NVMe
instance store volumes. Every instance has at least one network interface
attachment. For example, if you have no additional network interface attachments
on an EBS-only instance, you could attach 27 EBS volumes to that instance.

Launching a bare metal instance boots the underlying server, which includes verifying
all
hardware and firmware components. This means that it can take 20 minutes from the
time the instance
enters the running state until it becomes available over the network.

Bare metal instances use a PCI-based serial device rather than an I/O port-based serial
device.
The upstream Linux kernel and the latest Amazon Linux AMIs support this device. Bare
metal instances
also provide an ACPI SPCR table to enable the system to automatically use the PCI-based
serial device. The
latest Windows AMIs automatically use the PCI-based serial device.